This invention relates to airborne magnetic toner recovery; and, more particularly to demagnetizing magnetic tone which is recovered by magnetic scavenging.
There has recently been introduced a magnetic imaging system which employs a latent magnetic image on a magnetizable recording medium which can then be utilized for purposes such as electronic transmission or in a duplicating process by repetitive toning of the latent magnetic image with magnetic toner. Such magnetic imaging schemes are disclosed in U.S. Pat. Nos. 3,804,511 to Rait, et al; in 3,626,114; in 2,793,135 wherein a premagnetized surface is thermoremanently erased and in U.S. Pat. Nos. 3,611,415 and 3,368,209 wherein latent magnetic images are thermoremanently formed and developed.
Once the latent magnetic image is formed, it is developed with magnetic toner or developer material thereby being rendered visible. During development, some of the magnetic toner becomes airborne as the magnetic tape passes through the toner. The faster the tape speed, the more airborne toner there is.
One technique for removing airborne magnetic toner from the system is to magnetically attract the magnetic toner. This technique is referred to herein as magnetic scavenging. While this technique is quite efficient in the removal and recovery of magnetic toner, it does tend to polarize the toner; i.e., to permanently magnetize the toner.
As a consequence of this polarization of magnetic toner, the toner loses some of its flowability and tends to aggregate, agglomerate or clump together magnetically in the recovery process.